Inertia switch



Jan. 19, 1960 R, M, zlEsLER, JR 2,921,999

INERTIA .SWITCH Filed April l, 1957 9% ark,

Wi/Wai. Rober? M Ziegler, Jr.,

y k (99m:

United States Patent INERTIA SWITCH' Robert' Ziegler, Jr.,.Los Angeles,Calif., assignor to Hughes Aircraft Company, Culver City, Calif., acorporation'of Delaware Application April 1*, 19'57, Serial Noa 650,0466 Claims. (C1. 20o-61.52)

The present invention relates generally -to switch mechanisms andrelates more specifically tof switches of theinertia type, physicalmovement thereof being adapted to' effect interconnection betweencontact elements.

.Heretofore, inertia type switches have been known' that employ movingelements, at least a portion of which comprises a Weight member. Theseweight members are usually connected to shafts or arms and movementthereofunder inertia induced forces serves to move the weight and'yshaft or arm. TheV sh'afts or arms used in this type of mechanism havegenerally been arranged in such amanner as to effect closure of contactmembers. These prior structures have had numerous disadvantagesinasznuch as high friction forces are usually present, thus tocreatelubrica'tion problems. Additionally, these struc# tur'esl'iayebeen heavy, physically of a large size, employed many small complexparts, required considerable wiring operations during assembly and werenot well suited for .mass production' manufacturing techniques. Inoperating characteristics of prior devices, it has been common to employ--at least 50% of the weight mass in order to produce' a' contact forceand' when this factor is' coupled with problems relating to contactcleanliness, many failures of the prior structures have resulted. Inprior mechanisms that employ springs of various` types, itV isdesir/'able' .that suitable preloading of the springs be 'accomplishedbefore use of the switch. Prior devices have' been constructed in such amanner as to prevent adequate and reliable adjustment means forsettingspring preloading'. Y

Y It is, accordingly, one object of the invention to provideaniiietiaswitch mechanism having features of novelty and functionalcharacteristics to overcome the beforementioned difficulties andproblems associated with prior devices intended for a similar purpose.

l It is another important object of the invention toptovide' inertiaswitch mechanism that is extremely simple iiiA construction, reliable inoperation, eicient in use,

relatively inexpensive and of a nature enabling manufacture thereofl inmass` production situations.

It is a further important object of the invention to provide an inertiaswitch mechanism wherein a weight ni'e'ibei actsphysically to connect aplurality of contacts whereinl a wipingy action is established betweenthe Weight member and the contacts, thereby to promote eicientelectricalV connection between the contacts and the weight member.

Itis still another object of .the invention to provide an inertia switchmechanism wherein many of the components thereof are structurallycombined, thus to reduce' the over-all number of components and providea more simple" and inexpensive structure.

A further important object of the invention is to provide a switchmechanism `adapted for operation upon application'of inertia forcesthereto and wherein a spring biasing means applied to a movable weightmay be adiusted for preloading thereof, thus to establish more nearlyspring rate characteristics.

Other and further important objects of the invention will` becomeapparent from the disclosures in the' following detailed specification,appended claims and accompanying drawing, wherein:

Figure 1 isa longitudinal sectional view of the switch mechanism of thepresent invention and showing the components in position prior toinertia induced movement thereof;

Fig. 2 isan isometric View showing one of the composite contact members;

Fig. 3 is an isometric view showing a subcombination of the assembly ofthe present switch together with another of the composite Contactmembers; and' Fig. 4 is a longitudinal sectional view similar to Fig. 1,showing a modification of the invention.

Withreference to the drawing, it is fto be noted that the present*inertia switch mechanism comprises a tubular member 10 that may beconstructed from any suitable material and is preferably nonconductive.They tubular member 10 has an internal cylindrical bore 11 and a recess12 wit-h one end thereof. The other end of the member 10 isVA reduced indiameter and threaded as at 13'.

An'- insert 14, of nonconductive material, is disposed in thecylindrical bore 11 and has a flange 15 that is adapted toI overlie anend of the member 10. A contact member 16 is disposed about the insert14 and between the outer' surface of the insert and the bore 11. Thecontact member 1:6 has a plurality of tabs 17 bent from one end thereofand? adapted for disposition between the one end of the member 10 andthe fiance 15. A threaded sleeve 18 is adapted to engage t-he threads15, the sleeve having a radially inwardly extending flange 19 that is inturn adapted to engage an outer surface of the flange 1S whereby tosecure the insert 14 and the Contact member 16 in position withinthebore 11. The sleeve 18 is also constructed from a nonconductivematerial. As shown primarily in Figs. l and 2, the contact member 16further includes a tubular portion 20 that is constructed from a atsheet of material and rolled into the tubular form, thus defininglongitudinally extending, adjacently disposed free edges 21. To enableelectrical connection to the metallic contact member 16, an ntegral lug22 is disposed therefrom and extends through a suitable slot (not shown)in ythe flange 1S. In accordance with the usual practice, the lug 22 isprovided with an opening therethrough to facilitate attachment'of a wirelead. The end of the cylinder 20, remote from the tabs 17, integrallysupports a plurality of contacts 23 that are supported on angularlyinwardly directed end portions 24 formed from integral extensionportions Z5. The contacts 23 are in the form of dimples in the materialof thel contact member 16 and the outer raised portions thereof mayeither be coated with a highly conductive material such as silver or thelike, or may have a finite layer of silver deposited thereon.

`Another Contact member is indicated generally at 26 and is disposed inan end of the bore 11 remote from the insert 14. With reference to Figs.l and 3, the contact member 26 comprises a threaded shank portion 27having al disc 28 formed integrally on one end thereof. A cylindricalcontact carrying member 30 is disposed in an annular groove in the disc28 and secured thereto as by soldering, for example.- The member 30 issimilar in construction to the previously described cylinder 20, beingconstructed from a rolled sheet of material and having adjacentlongitudinal edges 31. A plurality of integral extension portions 32 aredisposed from one edge of the member 30 and have angularly, radiallyinwardly directed portions 33 integrally disposed therefrom.A Theportions 33 are adaptedlto carry dimpled contacts 34. As shown in Figi,a transversely disposed supporting web 35 is positioned within themember 30 and secured thereinby means of soldering or the like.Additionally, the web 35 is provided with a central opening 36, theshank 27v and high rate mass production of these integral components. i

While the contact members hereof are shown as being provided with threeequallyfcircumferentially spaced contacts that are carried by theangularly disposed members, it is to be understood thatV any number Vofcontacts may be provided commensurate Ywith the ultimate use thereof inparticlarsstructures. The 4triangular arrangementl of the contacts andthe angular disposition thereof provides a kinematic structure as isdesirable in the present instance. k-

An end closure member 38 is threadably disposed in the recess 12 in oneendA of the tubular member 10, the

Aclosure member havingareducedfdiameter portion 40 which extends intothe bore-11. A sealing ring member 41 isv disposed in a suitable groovein the portion 40 for cooperation between the closuremember 38 andthebore 11. The'outer end surface of the member 38'is provided with crosscut grooves 42 to enable application of tools for disposing the closuremember in the recess12. The closure member 38 has a central threadedbore '43 in which the shank 27 isr threadably disposed, the outer vendof the shank extending beyond the outer surface ofthe member 38 andhaving a nut 44 carried thereby, a contact terminal l45 being adaptedfor disposition between the nut 44 and 'the outer surface of themember'38, thereby to'lprovide an electrical connection for the contactmember The 'l nut 44 also serves to lockthe shankl 27 with respect tothe closure member 38, the shank 27 being provided with flattened areas46 on the exposed end thereof, whereby to permit application of toolsfor turningv the shank and the contact member 26.V -f ijf@ Withreference again to'Fig. 1a weight in the formof a spherey47 is disposedwithin the bore 11 and intermediate the contacts 23 and 34. The sphere47v maybe made from any Vsuitablepreferably Vdense metallic -rnateria1,

thus to enable both a weight function'and a Contact con nectingfunction. A tension spring 48 has one end 50 disposed through a bore 51in the sphere 47 and connected to the sphere as by soldering 52. Thespring48 Vextends through'a Ycentral areabetween the contact portions 24and is confined within abore 53 inthe inse'rtv14.l Another end of thespringy 48'has Van extension portion 5.4`that is disposed through acentralbore 55V in a threaded stud 56.l Thestud 56 threadably engagesthe insert 14 and extends outwardly therefrom. "The spring Vportion 54has a ball V57 secured thereto and disposed outwardly from the outer endof the bore 55; The ball S7 issecured to the stud 56 as by soldering 58,The outer end'of the' stud 56 `is also fitted with a nut 60 that isadapted to secure the stud against rotation relative to the insert 14and to confine a terminal 61 about the stud. The terminal 61 serves toprovide means for establishing electrical connection'with the sphere 47by way of the stud 5,6 and spring 48;

In initial assembly of the present device, the contact member 16 andinsert 14 are secured in position, together with the sphere 47 andassociated spring 48. The portion 50 of the spring 48 is extendedoutwardly through the opening 36 and bore 37 inthe Ycontact member 26and closure member 38 respectively and provided with a hookk shown bythe dotted lines at 62 Vin Fig. 1. The hook 62 serves to provide meansby which a predetermined tension may beapplied to the spring 48, wherebyto,V establislitheforce j ofY the sphere 47 against the.` contacts 323.p .'Iherefj after the end portion of the spring 48 is cut off adjacentthe soldered joint 52 and thecontact member 26, together with the endclosure member 38, are again installed in position. The outer end of thebore 37 may thereafter be closed as by any suitable material. y

Under inuence of acceleration in an axial direction of thetubular'member 10, and rightwardly as shown in the drawing, the sphere47 will be moved leftwardly against the Vtension of the spring 48 and atapredetermined value of acceleration, whereby to breakthe normalcontact, be-- tween the sphere and the contacts.23. Ata highervalue ofacceleration, the sphere will have completed its leftward movement tothe position'shown by the dotted lines in Fig. l, whereby to makecontact with the contacts 34. The relative axial positions of thecontacts 23 and 34 are adjusted by use of the shank 27. It is to benotedthat as the sphere 47 makes contact with the contacts 23 or 34,

f A the angularly'disposed portions24 or 33 respectivelyA will bedeformed, whereby to provide a wiping action between the contacts andthe` surface ofthe sphere 47.1Y The spring characteristics vof thematerial ofthe cylinder 2tland the member 30 serves to return theportionst24 and 33 to their Y e original positions followingdisengagement thereof by the sphere 47. The sphere 47 is maintained inaxial alignment with the contacts 23 and 34 by close confinement thereofwithin the bore 11. Due to this particular construction, movement of thesphere 47 may be accomplished only upon axial movement ofthetubularmember 10 and asso;

ciated structure, lateral 'movement of thesefstructures having no effectupon the contacts. z,

In connection with the specifcffunctional characteristics of thepresen-t switch arrangement, it should be pointed'out that Vthe contactclosing'value 'ofacceleration is a function. of the rate of the spring48,' the mass of Y' the sphere 47 and the spacing betweenvthe sphere andthe contacts. Additionally, the acceleration sensitivity of such astructure is a function of the Vmass of the sphere and the springvrate.- In many installationalv situations, the desired spring ratesfor aparticular range of acceleration vmay easily be obtained through uselofiberyllium copper springs, thereby to minimize the series resistanceto the moving contactas defined by the sphere 47. ,The contact portions24 and 33 are preferably flexible enough todeilect slightly uponcontactbythe sphere, thus to provide the before-mentioned wiping action. Theuse of the present axially movablecontacts not only permits a lowercontact resistance but also insures greater reliability for thestructure. 'Additionally, accurately dimensioned spheres are readilyobtainable and are relativelyinexpensive and compact, as compared topivoted weight arrangef ments. The particular kinematic arrangement ofthe Y contacts Vand the specificV structuralcharacteristicsthere-y l ofvserve to Aeliminate any tendency of the sphere tobounce 's lrelative tothe contacts andV no damping of the'action is required ,The relativelylarge available adjustment of the axial relative positions of thecontacts 23 andV 34 serves to compensate'fortolerance differences in the`dej f vicer'andV for'varying spring rates.

Furthermore, since the connections` are relatively widely spacedinsulation resistancek ashbetween ythese contacts is Vrelativelylhigh and Ithepossibility of voltage breakdownis extremely low;

In Fig. 4v a modiiicationi of the invention is shown `wherein like partsare indicated-by single primed referf ence characters. In this formofthe invention, the insert 14' has a spring element 63 disposedrwithinVthe recess 53 and secured thereinuby means of aV press lit. A pluralityof spring members 64 are disposed from oneend of the spring element 63;Additionally, aportion 50 of the spring 48 has a sleeve 65v securedthereto, one end of the sleeve Vbeing disposed in a suitable recess 66in the sphere 47.A `Theother end of the sleeve 65 isY provided with anannular enlargement 67 that normally is con-IY tained within theconfines of the spring members 64;l I 'jInthis modilied formof theinvention, 'it-may' thus'fbe seen that as inertia forces a'reappli'edtotheasphere 4'1,

agence@ the force' of the sprin-'ggmember 6'4 must' be overcome beforethe sphere may "move in' a leftward direction: When the force of, thespring members 64 is overcome, the enlargement 67 will be' pulleditherethrough, thus providin'g a snap action for engagement of the sphere47 with the contacts 34 and for separation ofthe sphere from thecontacts 23. The spring member 64 servesalso to retain the sphere 47 incontact with the contacts 34 until a reduction in inertia forces reachesa-level to permit the spring 48 to againdgraw the enlargement 67 throughthe spring member 64. Aconstruction of this type insures positive actionof the device when'engaging the contacts and less time between releaseof one setof contacts and engagement With'another.

vHaving thus described the invention and thepresent embodiments thereof,it is desiredto emphasize the fact that many further modifications maybe resorted to in a manner limited only by a just interpretation. of thefollowing claims.

I claim:

l. An inertia electrical switch apparatus comprising, in combination:Van elongated tubular housing; closure members threadably engaging eachlongitudinal end of said housing; a pair of contact Ncarryingstructures; one of said structures comprising a tubular portionhavingmeans for retaining said portion in association with one of saidclosure members and in one end of said housing, the other of saidstructures comprising a tubular portion; means for longitudinallyadjustably connecting said other of said structures to ano-ther of saidclosure members; a plurality of contacts carried by each of saidstructures and disposed in opposed spaced relationship within saidhousing; a spherical weigh-t disposed in said housing intermediate saidcontacts; tension spring means connected with said weight and said oneof said closure members for biasing said weight into normal contact withcontacts carried by one of said structures, inertia forces being adaptedlongitudinally to move said weight into contact with contacts carried bysaid other of said structures; and means for providing independentelectrical connection with said contact structures and said weight, saidconnection with said weight including said tension spring means.

2. An inertia electrical switch apparatus comprising, in combination: anelongated tubular housing; closure members threadably engaging eachlongitudinal end of said housing; a pair of contact carrying structures,one of said structures comprising a tubular portion having means forretaining said portion in association with one of said closure membersand in one end of said housing, the other of said structures comprisinga tubular portion; means for longitudinally adjustably connecting saidother of said structures to another of said closure members; a pluralityof contacts carried by each of said structures and disposed in opposedspaced relationship within said housing, said contacts being disposed atan acute angle relative to an axis of said housing and in spacedcircumferential relationships to each other on each of said structures;a spherical weight disposed in said housing intermediate said contacts;tension spring means connected with said weight and said one of saidclosure members for biasing said weight into normal contact withcontacts carried by one of said structures, inertia forces being adaptedlongitudinally to move said weight into contact with contacts carried bysaid other of said structures; and means for providing independentelectrical connection with said contact structures and said weight, saidconnection with said weight including said tension spring means.

3. An inertia electrical switch apparatus comprising, in combination:any elongated tubular housing; closure members threadably engaging eachlongitudinal end of said housing; a pair of contact carrying structures,one of said structures comprising a tubular portion having means forretaining said portion in association with one of said closure membersand.- inone end.V of said housing, Vvthe other of saidv structurescomprising a tubular portion;l

means for longitudinally adjustably connecting said other of saidstructures to another ofr said closure'members; a plurality of resilientcontacts'carried by each of said structures and disposedy in opposedspaced relationship within said housing; afspheric'al weight disposedand laterally closelyV confined in said housing intermediate saidcontacts; tension spring means connected with said weight and adjustablyconnected said one of said closure members for biasing saidfweight intonormal contactwith contacts carried' by one. of said structures, inertiaforces being adapted longitudinally to move said weightv into contactwith contacts carried by said other of said structures, said sphericalweight contacting said contacts with a wiping action; andv` means forproviding independent electrical connection Withsaid contact structuresand. said weight, said connection with said weight including saidtension spring'vmeans.

4. An inertia electrical switch' apparatus comprising, in combination:an' elongated'ftubular housing; closure members threadably engagingveach longitudinal end of said housing; a'pair of contact carryingstructures, one of said structures comprising a tubular portion havingmeans for retaining said portion in association' with one of saidclosureV members and in one end of said housing, the other of saidstructures comprising a tubular portion; means for longitudinallyadjustably connecting said other of said structures to another of saidclosure members; a plurality of resilient contacts carried by each ofsaid structures and disposed in opposed spaced relationship within saidhousing, said contacts being disposed at an acute angle relative to anaxis of said housing and kinematically arranged in spacedcircumferential relationships to each other on each of said structures;a spherical weight disposed and laterally closely confined in saidhousing intermediate said contacts; tension spring means connected withsaid weight and adjustably connected to said one of said closure membersfor biasing said weight into normal contact with contacts carried by oneof said structures, inertia forces being adapted longitudinally to movesaid weight into contact with contacts carried by said other of saidstructures, said spherical weight contacting said contacts with a wipingaction; and means for providing independent electrical connection withsaid contact structures and said weight, said connection with saidweight including said tension spring means.

5. An inertia electrical switch apparatus comprising, in combination: anelongated tubular housing; an insert in one end of said housing; aclosure member threadably engaging the other end of said housing; a pairof contact carrying structures, one of said structures having a tubularportion disposed about said insert and tab means disposed over an end ofsaid housing; a threaded retainer carried by said one end of saidhousing for securing said insert and said one of said structures inposition; shank means for longitudinally adjustably connecting the otherof said structures to said closure member; a plurality of resilientcontacts carried by each of said contact'carrying structures anddisposed within said housing in opposed spaced relationships, saidcontacts being arranged in groups of three, disposed at equal acuteangles relative to an axis of said housing and kinematically arranged inspaced circumferential relationships in each group thereof; a sphericalweight disposed and laterally closely confined in said housingintermediate said contacts; a tension spring disposed in a recess insaid insert having one end secured to said weight and the other endadjustably connected with said insert whereby to bias said weight intonormal contact with one of said groups of contacts as carried by saidone of said structures, inertia forces being adapted longitudinally tomove said weight into contact with the group of contacts carried by saidother of said structures, said spherical weight deecting said contactsupon engagement therewith to provide a wiping action therebetween; andmeans proyiding independent electrical con- :r'iectionl with saidcontact carrying structuresV and Vsaid weight', saidelectricalconnection with said weight including said tension Spring. Y Yf "6. An inertia electrical switch apparatus comprising, in combination:an elongated tubular housing; Van insert in one end ofrsaid housing; aclosure member threadably engaging theother end'of said housing; a pairof contact carrying structures, one of said structures having a tubularportion disposed about said insert and tab means disposed over an end ofsaid housing; a threaded retainer carried by said one end of saidhousing for securing said t insert and said one of said structures inposition; shank means for longitudinally radjustably connecting theother of said structures to said closure member; a plurality of rresilient contacts carried by each of'said contact carrying structuresand disposed withinV said housing in opposed spaced relationships, saidcontacts being arranged in groups of three, disposed at equal'acuteangles relative to an 'axis of said housing and kinematically arrangedin spaced circumferential relationships in each group thereof; aspherical weight disposed and laterally closely conned in said housingintermediate said contacts; a tension spring disposed in a recess inusaid insert having one end secured toY said weight and the other endadjustably i connected with said insert whereby to bias said weight intonormal contact with one of said groups of contacts as carried by saidone`f saidstructures, vinertia forces being adapted longitudinallyftomoveV said `weight into contact withrthefrgroup' of contacts carried bysaid other ofsaid structures, said spherical weightV deecting saidcontacts upon engagement therewith to provide a wiping actiontherebetween; leaf spring means disposed in said insert recess; anenlargement carried by and disposed froml said weight, said enlargementbeing adapted for cooperationV with -said leaf spring means to releasesaid weight with a snap action upon inertia induced or spring biasedmovement thereof; and means providing Vindependent electricalconnectionkwith said ycontact carrying structures and said weight, saidelectrical'connection with said weight including said tension spring.

References Cited in the iile of this patent A' UNITED STATES PATENTSBusacker et al vNovv. 18, 1947 Waldow May 2(7),71958

